Halloween was about sex before it was about "trick or treat," and the wonder is that we ever saw it any other way.

Let's see here: We have a sexy witch, a sexy nurse, a sexy majorette, a sexy bumblebee, a sexy pirate, and a sexy detective wearing a sexy deerstalker. There is a sexy Super Girl, a sexy Snow White, a sexy Strawberry Shortcake, and a sexy Little Bo Peep, not to mention a sexy Dorothy, a sexy Glinda, a sexy Scarecrow, and a sexy Cowardly Lion (imposerous!). Submarine Sally is sexy sailor. Backdraft Babe is a sexy firefighter. Officer Tara U. Clothesoff is a sexy policewoman, who should probably investigate whichever Girl Scout troop has a sexy girl scout (Don't Touch My Cookies) offering up her thin mints. You want sexy American history? Perhaps Pocahottie (sexy Pocahontas) or Pilgrim's Pleasure (sexy pilgrim) is for you. These are some of the women's disguises hanging on the walls of a Manhattan costume shop I visited last week, a place whose sexy costume section has a sexy costume for everyone. You can be a sexy French maid (Upstairs Maid, Francesca the Maid, Maid My Day), or you can be a sexy cat, or you can be both — Maid PurrFect — at the same sexy time.

The sexy costume is now as much a part of Halloween as candy corn and Tootsie Rolls, both of which, incidentally, are available in sexy-costumeform. But how did we get to this point? Provocative dress seems like a modern phenomenon, especially to all those parents who remember wistfully when their daughter's Alice In Wonderland costume didn't include a garter belt. But a quick spin through history suggests a more complicated story, one that involves everything from the potato famine to 19th-century class and race relations to the globalized marketplace of the 21st century. Halloween was about sex before it was about "trick or treat," and the wonder is that we ever saw it any other way.

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The early costumes were decidedly unsexy. In Dressed for Thrills: 100 Years of Halloween Costumes and Masquerade, essayist Mark Alice Durant writes that people disguised themselves as animals during Samhain, a Celtic festival and a precursor to Halloween, to allay the restless souls of the dead. Centuries on, people celebrated the Catholic festivals All Saints' Day and All Souls' Day (additional influences on modern Halloween observances) with parades, wild parties, and more costumes — in some cases boys cross-dressed as girls. All Saints was supposed to honor the saints and martyrs of the Roman Catholic Church, but as historian Nicholas Rogers writes in Halloween: From Pagan Ritual To Party Night, it wasn't long before sex entered the discussion: "Its liturgy also referred to ‘the wise virgins awaiting the coming of the bridegroom' thereby anticipating forthcoming marriages and a replenishing of the Christian flock." By the 19th century, Halloween held special significance as an occasion for predicting wedding bells. A once-death-obsessed holiday had blossomed into something more life-affirming. Rogers explains:

The way stones settled in bonfires, the way nuts cracked in the hearth, the shape of kale stalks pulled from the ground, the people or sounds one encountered at the midnight hour at a crossroads or stile — all were windows to the future. Some of these rites foretold forthcoming deaths, a predictable message in view of the holiday's long association with the dying, and one that in Ireland persisted in the aftermath of the potato famine of the mid-nineteenth century. But where killer epidemics declined in potency and the demographic fortunes of young people began to improve, at least after infancy, the spells and omens of Halloween increasingly focused upon future marriage prospects: who, when, whether one would marry; whether one's partner would be handsome or faithful or chaste at marriage.

In villages at the time, everything from where you slept to where you worked, was divided strictly according to gender. As a result, one of the few places where young couples could flirt and court was at public festivals, like Valentine's Day and May Day. "Halloween became one of those occasions in the ritual year," Rogers writes, "when young adolescents tried to channel their sexuality into more permanent union."

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Whence sexy costumes? "The historical precedent would be the sexy costumes at masquerade balls, which were wildly popular from the 18th and 19th century on," says Valerie Steele, director of the Museum at FIT. "Respectable women would wear pantaloons or short skirts and milkmaid outfits when they went to costume parties. At the masquerade parties in London, you had costumes with a degree of body exposure. You also had artists' balls — in Paris especially — where you had revealing costumes and some nudity."

We've long had sexy costumes; it's just that the boundaries of "sexiness" have changed. In The Masked Ball at the Opera, an 1873 oil painting by French impressionist Édouard Manet, women are depicted in disguises that show off their legs — a bold subversion of the social mores of the day. One even appears to be wearing a sailor's outfit. "That would've been the equivalent of today's sexy pirates," Steele says. Back then, throwing on a costume, provocative or not, was a potent form of escapism. "Any time you're allowed to wear a costume, you're also allowed to engage in activities outside your normal behavior," says Nancy Deihl, director of costume studies at NYU Steindhardt.

In effect, costumes created a shadow world wherein one could indulge tastes for sex or booze or gambling without social or official sanction. In theory, anyway. In Venice, where masquerades and debauchery walked hand in hand for centuries, officials had to pass laws limiting the use of masks because people were behaving so licentiously.

Costumes have always had an undercurrent of outlaw sexuality about them. Frequently, they're wrapped up in the prevailing taboos of the day. Consider the maid costume. During the 19th century, domestic servants poured into the households of the middle class. Soon, memoirs and novels began documenting maids' erotic appeal. Nathaniel Hawthorne wrote lovingly of one servant, "her handkerchief somewhat displaced from her white bosom ... her bare arms in the water ..." As Jill Fields, a history professor at CSU-Fresno and the author of An Intimate Affair: Women, Lingerie, and Sexuality, tells it, any woman who had to work for a living violated basic Victorian standards of decency, so domestic helpers were, by definition, not "ladies." They were seen as working girls in at least one sense of the phrase. Their uniforms only reflected their status. "At a time when dress was establishing a veritable barrier between the sexes, the apron evoked a feminine undergarment and suggested easy intimacy," Fields quotes the 19th-century sexologist Richard von Krafft-Ebing as saying. The fact that many domestic servants were black introduced a frisson of racial taboo. A 1923 French ad for maids depicted a black woman emerging from a wooden box, mailed from Martinique to France. She wore only a maid's cap and skimpy apron — suggesting that her duties as a servant included much more than just dusting the shelves.

Fast-forward to the second half of the 20th century. "The '70s is when you really see an explosion of adult costumes," Valerie Steele says. "It was the decade of sexual liberation — the Me decade." It was the birth of The Rocky Horror Picture Show, that cult icon of sexual deviance, with the campy maid costumes and Tim Curry in a corset. It was also when the celebration of Halloween spilled out onto the streets and into nightclubs, after decades in churches, community centers, and suburban homes. You could rent glittery costumes and behave much as the masked revelers had done in London centuries earlier. (It's no accident that New York City's now-famous Halloween parade, a spectacle of skin and outrageous fashion, got underway in 1974.) Today, we think of all that overt sexuality as somehow veering from the child-like soul of Halloween. In truth, the holiday's sanitized 1950s version — with the cutesy home decor and the kids trick-or-treating politely in the suburbs — was likely the greater anomaly.

What's different now, of course, is that the permissive sexuality of the 1970s has been normalized — co-opted by mainstream culture — and packaged in flimsy plastic wrap for average (largely female) consumers. Nancy Deihl speculates that today's sexy costumes can be traced, in part, to the general immodesty of contemporary women's clothing, a trend that got underway in the 1920s and hasn't stopped since, not even to straighten a micro-mini. As mass media became more frankly sexual, so too did Halloween costumes.

Deihl suggests that the proliferation of sexy dress might have its roots in a more modern phenomenon: globalization and the rise of cheap manufacturing overseas. Or, as she puts it, "the emergence of China as a source for everything manufactured and the creation of new markets for odd products so that even the most low-key holidays now require a host of accessories for body and home." Certainly, risque costumes lend themselves to elaborate accessorizing. If you buy the polyester French maid outfit, you also have to buy the sexy fishnet stockings and the sexy five-inch platform heels and the sexy ruffled panties, and, not to be forgotten, the sexy pink duster. People spring for the stuff because it's mass-produced and therefore cheap, and no one cares if it looks cheap, because it doesn't need to last longer than a night.

For retailers, it's a gold mine. HalloweenMart.com, a major online retailer, has said that sexy costumes count among its top sellers. In Bloomington, Indiana, Campus Costumes has had to ratchet up its order of barely there costumes every year since the store opened. Last fall, Victoria's Secret started offering Halloween costumes that are virtually indistinguishable from the company's lingerie. Frederick's of Hollywood, Victoria's Secret's sleazy sister, has been pushing sexy Halloween costumes for years and has said that Halloween is its third-largest season after Valentine's Day and Christmas.

Sexy costumes probably aren't going anywhere. Halloween will go on producing legions of fairy-tale strumpets and firefighters who certainly don't look like they could save anyone's life, because in one way or another Halloween has always been about replenishing the flock. It's big business now, and as those in the $6.8 billion American Halloween industry will tell you, money is always sexy. Not surprisingly, a sexy-money costume can be yours for $32.99.